Sea Hare as harvest helper

[Cuttlefish]

I have a large piece of table coral (skeleton) and I placed into my refugium 6 weeks ago. I let algae grow on this thing unchecked for the entire time. You woldnt believe the variety of forms of algae that has grown on this bleached coral. But it thick and is infested with beneficial pods.

So what I was thinking was, instead of taking this coral out of the tank and cleaning (harvesting) the algae, why not let my sea hare mow it down and then Ill just suck the poop out manually. At the rate this thing eats, he will have turned this entire crop of turf into poop in a couple days. A couple times a day, for two days I have no problem starting a quick siphon and sucking the new poop out, until the job is done. Ive been using him as a remote algae cleaner when my coralline was starting to brown. Id put him where Id want no algae and he'd do the job as soon as he was placed on the surface. This sea hare is really a poop machine to be honest. He eats and poops and sleeps, thats his life.

The question is, will the algae's phosphates still be contained within the poop or will nutrients also be released back into the water by urine?